With the development of electronic products trending to high resolution and portable devices, pitches between pads for connecting display panels and components are becoming smaller and smaller, it brings opportunities and challenges to the design and production of display panel products.
In general, a screen of an organic light-emitting diode (OLED) display panel may be simply divided into an active area (AA) and an outer lead bonding (OLB) portion, and the OLB portion may include a bonding pad portion. A peripheral circuit including the outer leads may include an integrated circuit (IC), a chip on flex (COF), a flexible circuit board (FPC), and a printed circuit board (PCB) or the like, which are bonded to a corresponding bonding pad portion of the display panel via an anisotropic conductive film (ACF). It may achieve a display control of the AA of the display by external signals sending from the peripheral circuit.
The design of a bonding pad in the bonding pad portion mainly considers two aspects for a bonding process. First, an overlap between the peripheral circuit and the display panel; second, a distance between bonding pads. A size of the overlap needs to be large enough to capture more conductive particles, to make an upper and a lower electrodes to be a conductive path, and the distance between two adjacent bonding pads needs to be large enough to prevent from a short circuit occurring between the adjacent bonding pads. However, a shape of the bonding pad and an arrangement of the bonding pad widely used in the bonding pad portion of the OLED display, are in general regular rectangles. When the bonding pad wants to be formed to a small fine pitch design, it will bring greater challenges in display panel processes and designs.